The present invention relates to a method and apparatus for applying a web component in a curved configuration onto a moving substrate web. More particularly, the present invention relates to a method and apparatus for applying web components in a curved configuration at each of the leg opening regions of a disposable absorbent article, such as a disposable diaper.
Limited use absorbent articles, such as disposable diapers, have incorporated elasticized gathers at the leg openings of the article. The leg openings are positioned at the lateral side margins of the article, and can be elasticized with a single web component or with multiple web components.
Various techniques have been developed for applying multiple elastic strands onto a substrate. It has been desirable to employ curved web components which better follow the contours of the leg openings formed in the side margins of disposable absorbent garments. For example, prior techniques have been employed to apply one or more elastomeric strands in a curved pattern along the length of a moving substrate. Prior techniques have also been employed to apply a curved elastomeric composite web along the length of a moving substrate.
Conventional techniques, such as those described above, have not provided an adequate system for efficiently placing a relatively wide web component, such as a wide elastic composite member, across a desired curvilinear location on the surface of a moving substrate. Such conventional techniques have not been able to provide desired amounts of curvature, and have generated excessive distortions in the web component. In addition, the conventional techniques have not been sufficiently adaptable to accommodate web components of different sizes.
Generally stated, the present invention provides a distinctive process and apparatus for applying a web component to a moving substrate. The technique of the invention includes a delivering of the web component to an applicator wheel. The applicator wheel has an entry surface-region, an exit surface-region, a transport surface-region, and an applicator wheel diameter. The web component is contacted onto the entry surface-region of the applicator wheel, and the web component is moved along a substantially circumferential, applicator path along the transport surface-region of the applicator wheel. The applicator wheel is oscillated about a pivot axis which is spaced from the moving substrate by a pivot distance, and the web component is applied from the exit surface-region of the applicator wheel onto the moving substrate to provide a curved web configuration.
In a particular aspect, the applicator wheel diameter can be at least a minimum, selected percentage of the pivot distance. Another aspect of the present invention can include a selective adjusting of an exit-span distance between the applicator wheel and an integration roll. A further aspect can include an urging of the component web against the moving substrate at a selected point that is located relatively downstream from a contact point at which the web component is applied to the moving substrate.
In its various aspects, the present invention can more effectively and efficiently assemble a relatively wide web component, such as a wide elastomeric composite member, along a desired curvilinear location on the surface of a moving substrate. The technique of the invention can provide larger amounts of curvature, and can reduce the generation of excessive distortions in the assembled web component. In addition, the technique of the invention can be readily adjusted to accommodate web components having different sizes.